Abstract
Intra-operative fractures of the femur are on the rise mainly due to the increased use of cementless implants and the desire to get a tight press fit. The prevalence has been reported to be between 1–5% in cementless THAs. The key to preventing these fractures is to identify patients at high risk and careful surgical technique. Surgical risk factors include the use of cementless devices, revision hip surgery, the use of flat tapered wedges and MIS surgery. Patient factors that increased risk include increasing age, female gender, osteopenia and rheumatoid arthritis. These risk factors tend to be additive and certainly when more than one is present extra caution needs to be taken.
Surgical technique is critical to avoid these intra-operative fractures. Fractures can occur during exposure and dislocation, during implant removal (in revision THA), during canal preparation and most commonly during stem insertion. In both primary, and especially in revision, THA be wary of the stiff hip in association with osteopenia or osteolysis. These patients require a very gentle dislocation. If this cannot be achieved, then alteration of the standard approach and dislocation may be needed. Examples of these include protrusion with an osteopenic femur and revision THA with a very stiff hip with lysis in the femur. Lastly, in cases with retained hardware, dislocate prior to removing plates and screws.
After dislocation, the next challenge is gentle preparation of the femoral canal. A reasonable exposure is required to access the femoral canal safely. MIS procedures do not offer good access to femoral canal and this probably results in increased risk of fracture during broaching or implant insertion. When broaching, stop when broach will not advance further. When inserting a tapered wedge stem, be worried if stem goes further in than broach.
In revision surgery, when taking the stem out from above, make sure the area of the greater trochanter does not overhang the canal. A high speed burr can clear the shoulder for easier access for removal. In revision THA with an ETO, place a cerclage wire prior to reaming and retighten prior to stem insertion.
Even with careful surgical technique intra-operative femoral fractures will still occur. When inserting the stem, a sudden change in resistance is highly suggestive of fracture. Wide exposure of the entire proximal femur is necessary to confirm the diagnosis. The distal extent of the fracture must be seen. Only on occasion is an intra-operative radiograph needed. Management is directed to ensuring component stability and good fracture fixation. In primary total hip arthroplasty, calcar fractures are by far the most common. If using proximal fixation and you are certain the stem is stable, then all that is needed is cerclage wiring. As already mentioned, you must follow the fracture line distally so you are aware of how far down it goes. Often what appears to be a calcar split actually propagates distal to the lesser trochanter. In these cases, one would probably go for distal fixation plus wiring.
In conclusion, intra-operative femoral fractures are on the rise. Prevention is the key.
